Serological and molecular survey of canine distemper virus in red foxes (Vulpes vulpes): Exploring cut-off values and the use of protein A in ELISA tests.

The wide distribution and ecological plasticity of the red fox (Vulpes vulpes) make it a potential reservoir for many infectious diseases shared with domestic and wild carnivores. One of such diseases is canine distemper, which is caused by an RNA virus and its main domestic reservoir is the dog. However, other carnivores can also participate in its maintenance, as shown by the recent upsurge of reported cases in wildlife in many parts of the world, and by the fact that red foxes may act as true reservoirs for canine distemper virus (CDV). The lack of validated serological tests for wildlife or other non-target species may be a handicap for monitoring this virus. In this study, serological assays were compared in 147 red fox sera using a commercial ELISA validated for its use in dogs and a non-specific modified ELISA with Protein A peroxidase conjugate to detect bound antibodies. In addition, the presence of CDV RNA in brain, spleen, lung, and liver samples from 144 foxes was investigated by a RT-qPCR. Through the comparison of the results of both ELISAs and the use of a finite mixture model of the optical density values obtained by both techniques, we adjusted the cut-off point of the commercial ELISA to obtain the seroprevalence in foxes. The overall seroprevalence detected was 53.7% (79/147) and 57.1% (84/147) by the commercial and modified ELISA, respectively, with a moderate agreement according to Cohen's Kappa statistic (κ = 0.491, z = 5.97, p < 0.0001). CDV RNA was detected in 30 out of 144 foxes, which resulted in 20.8% of CDV-infected foxes. At individual level, the results obtained by relating the serological status and the presence/absence of RNA in different organs were explained in terms of the pathogenesis of the infection. Our results highlight the convenience of adjusting the cut-off point when using an ELISA assay developed in domestic dogs for its use in foxes. Moreover, Protein A is confirmed to be a good alternative to be used in red foxes, presenting a good reactivity towards its IgG.

Long-term effect of a single application of organic refuse on carbon sequestration and soil physical properties.

Restoration of degraded lands could be a way to reverse soil degradation and desertification in semiarid areas and mitigate greenhouse gases (GHG). Our objective was to evaluate the long-term effects of a single addition of organic refuse on soil physical properties and measure its carbon sequestration potential. In 1988, a set of five plots (87 m(2) each) was established in an open desert-like scrubland (2-4% cover) in Murcia, Spain, to which urban solid refuse (USR) was added in a single treatment at different rates. Soil properties were monitored over a 5-yr period. Sixteen years after the addition, three of the plots were monitored again (P0: control, P1: 13 kg m(-2), P2: 26 kg m(-2) of USR added) to assess the lasting effect of the organic addition on the soil organic carbon (SOC) pools and on the physical characteristics of the soil. The SOC content was higher in P2 (16.4 g kg(-1)) and in P1 (11.8 g kg(-1)) than in P0 (7.9 g kg(-1)). Likewise, aerial biomass increased from 0.18 kg m(-2) in P0 up to 0.27 kg m(-2) in P1 and 0.46 kg m(-2) in P2. This represents a total C sequestration of 9.5 Mg ha(-1) in P2 and 3.4 Mg ha(-1) in P1, most of the sequestered C remaining in the recalcitrant soil pool. Additionally, higher saturated hydraulic conductivity, aggregate stability, and available water content values and lower bulk density values were measured in the restored plots. Clearly, a single addition of organic refuse to the degraded soils to increase the potential for C sequestration was effective.

Anthropogenic nutrient sources and loads from a Mediterranean catchment into a coastal lagoon: Mar Menor, Spain.

The Mar Menor is a coastal lagoon increasingly threatened by urban and agricultural pressures. The main watercourse draining into the lagoon is the Rambla del Albujón. A fortnightly campaign carried out over one annual cycle enabled us to characterize the treated urban sewage effluents and agricultural sources which contribute to the nutrient fluxes in the watercourse. Multivariate analysis provided information for establishing chemical signatures and for assessing the relative influence of the various sources on the water quality at the outlet. Mass balances were used to examine net gains and losses, and cross-correlations with rainfall to analyze climatic influence and control factors in the trends of the nutrient flux. The rainfall pattern was significantly cross-correlated with nitrate and phosphorus fluxes from agricultural sources, while fluctuations in the resident population explained the phosphorus flux trend in urban sources. 50% of dissolved inorganic nitrogen was from agricultural sources, while 70% of total phosphate and 91% of total organic carbon were from urban point sources. The net amounts of all the nutrients fell as a result of plant uptake and/or denitrification in the channel. The control of urban point sources (phosphorus-enriched) is suggested as a promptly action for improving the health of the coastal lagoon.

Aggregation of European storm-petrel (Hydrobates pelagicus ssp. melitensis) around cage fish farms. Do they benefit from the farms resources?

Cage aquaculture aggregates wild fauna due to food provision. Several seabirds frequent fish farms, including the European storm-petrel (Hydrobates pelagicus melitensis). This work investigates the presence of storm-petrels around two aquaculture areas interspersed between breeding colonies in western Mediterranean Sea. Contribution of aquaculture-derived resources to their diet was assessed. Storm-petrels were mist-netted at the colonies and marked by bleaching feathers. Density around aquaculture areas was estimated through visual counts. Marks recognition was conducted visually and by photo-capture. Storm-petrel regurgitates were used as target tissue to estimate diet sources contribution. Contribution of surface zooplankton, ichthyoplankton and aquaculture wastes was estimated through Bayesian mixing modelling combining carbon and nitrogen stable isotopes and fatty acids as biomarkers. Storm-petrel density was high in open-sea aquaculture area, but not observed around near shore farms. Temporal variability of storm-petrels density during the breeding season was linked to their reproductive phenology. Within the open-sea aquaculture area, bluefin tuna farm was more attractive for storm-petrels than seabream/seabass farms. Visual identification of bleaching marks was not useful. Photo-capture showed that 8.3% of the storm-petrels watched around farms were firstly trapped in some of the nearby colonies, and 91.7% were unmarked. Qualitative evidence of aquaculture-derived wastes utilization was obtained. However, its estimated contribution was low (4.3%) when compared to ichthyoplankton (61.1%) or zooplankton (34.6%). The studied open-sea farms significantly aggregated storm-petrels along their entire breeding season. Storm-petrels got a slight profit from aquaculture resources. Nevertheless, some concerns arise regarding the cost/benefit balance of the interaction.